Treatment of log yard run-off by irrigation of grass and willows

Log yard run-off is a potential environmental risk, among other things because it creates an oxygen deficiency in receiving watercourses. This study was conducted to investigate the purification efficiency of soil-plant systems with couchgrass (Elymus repens) and willows (Salix sp.) when intensively irrigated with run-off from an open sprinkling system at a Norway spruce (Picea abies) log yard. The purification efficiency was determined both at the field scale (couchgrass) and in 68-L lysimeters (couchgrass and willows). Groundwater in the field and drainage water from the lysimeters were analysed for Total Organic Carbon (TOC), distillable phenols, total P, and total N. Retention of TOC, phenols and P occurred but no difference between couchgrass and willows was observed. The system had better purification capacity at the field scale than in the lysimeters.     

Modeling mercury fluxes and concentrations in a Georgia watershed receiving atmospheric deposition load from direct and indirect sources

This paper presents a modeling analysis of airborne mercury (Hg) deposited on the Ochlockonee River watershed located in Georgia. Atmospheric deposition monitoring and source attribution data were used along with simulation models to calculate Hg buildup in the subwatershed soils, its subsequent runoff loading and delivery through the tributaries, and its ultimate fate in the mainstem river. The terrestrial model calculated annual watershed yields for total Hg ranging from 0.7 to 1.1 microg/m2. Results suggest that approximately two-thirds of the atmospherically deposited Hg to the watershed is returned to the atmosphere, 10% is delivered to the river, and the rest is retained in the watershed. A check of the aquatic model results against survey data showed a reasonable agreement. Comparing observed and simulated total and methylmercury concentrations gave root mean square error values of 0.26 and 0.10 ng/L, respectively, in the water column, and 5.9 and 1 ng/g, respectively, in the upper sediment layer. Sensitivity analysis results imply that mercury in the Ochlockonee River is dominated by watershed runoff inputs and not by direct atmospheric deposition, and that methylmercury concentrations in the river are determined mainly by net methylation rates in the watershed, presumably in wetted soils and in the wetlands feeding the river.     

Innovative aspects of environmental chemistry and technology regarding air,water, and soil pollution

Environmental Science and Pollution Research -     

Levels, sources and spatiotemporal variation of nutrients and micropollutants in small streams of a Mediterranean River basin

In this study, nutrients, trace metals and priority pesticide compounds were investigated for the first time in water and sediment samples in streams of the Evrotas River basin (S.E. Greece) from 2006 to 2008. The most important sources of contamination were from the entry of pesticides and nutrients into surface waters and sediments as a result of the intensive agricultural activity as well as from the uncontrolled disposal of olive mill and citrus processing wastewaters. Aquatic risk assessment revealed that all insecticides detected showed high risk, suggesting adverse effects on the stream biota. Among the metals analyzed, Cr, Ni and Ba presented the highest concentrations in sediments, however, due to natural geological processes. Multivariate statistical techniques applied for data compression, exploration and interpretation proved to be useful tools for identifying the most critical pollutants affecting the surface water quality. The findings of this study suggest that the inclusion of streams with small catchment areas into WFD monitoring and assessment programs is essential, especially those of the Mediterranean region.     

Chlorinated and brominated organic contaminants in fish from Shanghai markets: a case study of human exposure

In the present study were two favorite edible fish species for local residents, i.e., mandarin fish and crawfish, collected from the Shanghai market and analyzed for selected organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), hexabromocyclododecane (HBCDD), polybrominated diphenyl ethers (PBDEs) and methoxylated PBDEs (MeO-PBDEs). Efforts were also made to identify the potential sources of these contaminants. Comparable concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and HBCDD were found in muscle tissue of mandarin fish from Guangdong (GDF), the Pearl River Delta and from Taihu Lake (TLF), the Yangtze River Delta. Levels of chlordanes, PCBs and PBDEs were about one magnitude lower in TLF compared to GDF. The concentrations of OCPs in the butter-like gland of the crawfish (CFB) were 2-5 times of those in the crawfish muscle (CFM) while concentrations of PCBs, PBDEs and MeO-PBDEs were comparable. The different patterns and levels of chlorinated and brominated organohalogen contaminants seen in mandarin fish from GDF and TLF indicates that different types of chemicals might be used in the two delta regions. The present study also shows a good correlation between the concentrations of hexachlorobenzene (HCB) and pentachloroanisol (PCA) in fish for the first time. Fish consumption limits based on chemical contaminants with non-carcinogenic effects were calculated. The estimated maximum daily consumption limit for GDF, TLF, CFM and CFB were 1.5, 2.6, 3.7 and 0.08 kg, respectively, indicating no significant risk regarding the persistent organic pollutants measured in the present study.     

Novel imazethapyr detoxification applying advanced oxidation processes

Different degradation methods have been applied to assess the suitability of advanced oxidation process (AOPs) to promote mineralization of imazethapyr [(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid], a widely used imidazolinone class herbicide, the persistence of which has been demonstrated in surface and ground waters destined to human uses. Independent of the oxidation process assessed, the decomposition of imazethapyr always followed a pseudo-first order kinetic. The direct UV-irradiation (UV) of the herbicide as well as its oxidation with ozone (O?), and hydrogen peroxide tied to UV-irradiation (H?O?/UV) were sufficiently slow to permit the identification of intermediate products, the formation pathway of which has been proposed. Ozonation joined to UV-irradiation (O?/UV), ozonation joined to titanium dioxide photo-catalysis (TiO?/UV+O?), sole photo-catalysis (TiO?/UV), and photo-catalysis reinforced with hydrogen peroxide-oxidation (TiO?/UV+H?O?) were characterized by a faster degradation and rapid formation of a lot of small molecules, which were quickly degraded to complete mineralization. The most effective oxidation methods were those using titanium dioxide photo-catalysis enhanced either by ozonation or hydrogen peroxide. Most of all, these last processes were useful to avoid the development of dangerous by-products.